The present invention relates to a spray adjuvant useful in the application of pesticides for treating crops which alleviates phytotoxicity associated with chlorothalonil and to a method for preventing fungal diseases employing such spray adjuvant in combination with pesticides. The invention more particularly relates to a method for preventing fungal disease in crops such as banana crops in which a spray adjuvant is used which provides satisfactory uptake of a systemic fungicide such as propiconazole but minimizes the phytotoxicity of a contact fungicide such as chlorothalonil.
Systemic fungicides and other systemic pesticides are commonly applied to crops as an aqueous spray containing spray adjuvants such as surfactants and emulsified agricultural crop oils which insure that the pesticide is deposited as a droplet which wets the leaf and is retained on the leaf of the plant so that the pesticide can be absorbed. For example, banana spray oils (BSO), commonly used in combination with systemic fungicides in banana production, deposit an oily residue on the leaf surface which promotes the uptake of the systemic fungicide.
To reduce developing resistance to any particular pesticide, it is common practice to rotate pesticides. In some areas of the world, it is a common practice of growers to sequentially or simultaneously treat the crops with a systemic fungicide cocktail containing BSO and with chlorothalonil. However, an antagonistic response has been observed involving the oil and chlorothalonil resulting in unacceptable necrosis of leaf tissue.